Several series of double-helical DNA molecules will be synthesized in which base pair polarity, nearest neighbor environment and position in the helix will be systematically varied. The effects of these variables on base pair stability and helix-coil dynamics will be studied by high-resolution NMR at 500 MHz. The solution structure of these DNA duplexes will be investigated using the nuclear Overhauser effect to measure interatomic distances; time-resolved FT NMR will be used to measure base pair lifetimes in the helix by inversion recovery exchange methods. Subsequently several natural promoter, operator and terminator DNA sequences from several gene loci will be synthesized and each base pair monitored for stability and helix-coil dynamics. Several known point mutations in these control sequences which either increase or decrease their regulatory effectiveness (promoter-up, promoter-down, operator constitutive mutants) will then be synthesized and compared with the wild-type sequence to elucidate the physical correlates of regulatory function.